Science Nation: If These Teeth Could Talk

3 minutes

(male narrator)
It's as if these teeth
can talk.

(Peter Ungar)
These are replicas of the most
important fossil skulls
in the human fossil record.

(narrator)
Anthropologist Peter Ungar
uses casts of jaws,
teeth, and skulls
to study diets
of ancient animals
and how they have evolved
over time.
Here's a gorilla skull.
The teeth
on this thing are huge.
They're also very cresty,
which makes them
well-suited for grinding up
and shearing and slicing leaves
and other tough vegetation.

(narrator)
With support from the
National Science Foundation,
Ungar's team
at the University of Arkansas
study microscopic scratches
on thousands of teeth
from primates to dinosaurs.
Eating hard or tough things
could be hard work.

(narrator)
For years, scientists believed
that because early hominids
had huge teeth and jaws,
that meant their diets
were derived
of tough stuff
like seeds and nuts.
But using new tools like these,
Ungar can see minute abrasions.

(Ungar)
You can see the wispy
scratches across the surface.

(narrator)
Our ancestors were like us.
They'd rather eat something
soft and tasty
than something
hard to crack and chew.
Big teeth
and jaws only suggest
what they could eat
when food was scarce,
not necessarily
what they did eat
when tempting fruits
were plentiful.
Looking at the microscopic
wear on those teeth,
it's quite rare
to see the heavy pitting
one expects
from a hard-object feeder.
More often, there are
light, wispy scratches,
which is what
we see in soft-fruit feeders.

(narrator)
Observe the wear and tear
of this human ancestor's teeth.
Now look
at this monkey's teeth,
known to eat hard,
brittle foods.

(Ungar)
Instead of two or three microns
in depth, this is eight.

(narrator)
Ungar receives
dental casts of fossils
from museums worldwide.
Take our fossil,
and just squirt it
with this impression
material.

(narrator)
Casts are also made
from live subjects.
Ungar says more information
about ancient animal diets
will help shape
understanding of behavior,
migration patterns,
and evolution.

(Ungar)
They are like footprints--
records of something
the animal rejected.
It's cool to see that.

(narrator)
A new view of the past
you can sink your teeth into.
For Science Nation,
I'm Miles O'Brien.

With funding from the National Science Foundation, Peter Ungar is revealing more details about the lives of human ancestors, and he’s doing it through dentistry. The University of Arkansas anthropologist uses high tech dental scans to find out more about the diets of hominids, a technique that sometimes leads to new and very different conclusions. While anthropologists traditionally determine the diets of our ancestors by examining the size and shape of teeth and jaws, Ungar's powerful microscopes paint a more detailed picture by looking at wear patterns on teeth.